Re: [PATCH 4/4] drm/log: Batch vmap/vunmap and flush for record drawing

[Jocelyn Falempe <jfalempe@redhat.com>]

On 29/07/2026 10:48, oushixiong1025@163.com wrote:
> From: Shixiong Ou <oushixiong@kylinos.cn>
> 
> drm_log_draw_new_line() calls drm_log_clear_line() and
> drm_log_draw_line(), which independently call
> drm_client_buffer_vmap_local(), drm_client_buffer_vunmap_local(),
> and drm_client_buffer_flush(). For each call to
> drm_log_draw_new_line(), this results in 2 vmap/vunmap pairs and
> 2 flush calls, even though vmap_local maps the entire framebuffer
> each time.
> 
> Refactor drm_log_clear_line() and drm_log_draw_line() to accept a
> pre-mapped iosys_map by value, removing the per-line vmap/vunmap/flush
> calls. Move the single vmap/vunmap pair and flush up to
> drm_log_draw_new_line(), which now maps once before clearing and
> drawing, then issues a single flush after unmapping.

Thanks, it looks good to me.

I think you just need to remove the drm_rect in drm_log_clear_line() and 
drm_log_draw_line(), as they are not used anymore.

Best regards,

-- 

Jocelyn

> 
> Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
> ---
>   drivers/gpu/drm/clients/drm_log.c | 52 ++++++++++++++++++++-----------
>   1 file changed, 33 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/clients/drm_log.c b/drivers/gpu/drm/clients/drm_log.c
> index 63577aeb705c..4896b3e00710 100644
> --- a/drivers/gpu/drm/clients/drm_log.c
> +++ b/drivers/gpu/drm/clients/drm_log.c
> @@ -109,25 +109,21 @@ static void drm_log_blit(struct iosys_map *dst, unsigned int dst_pitch,
>   	}
>   }
>   
> -static void drm_log_clear_line(struct drm_log_scanout *scanout, u32 line)
> +static void drm_log_clear_line(struct drm_log_scanout *scanout, u32 line,
> +			       struct iosys_map map)
>   {
>   	struct drm_framebuffer *fb = scanout->buffer->fb;
>   	unsigned long height = scanout->scaled_font_h;
> -	struct iosys_map map;
>   	struct drm_rect r = DRM_RECT_INIT(0, line * height, fb->width, height);

only r.y1 is used, so you can remove this rectangle declaration

>   
> -	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
> -		return;
>   	iosys_map_memset(&map, r.y1 * fb->pitches[0], 0, height * fb->pitches[0]);
> -	drm_client_buffer_vunmap_local(scanout->buffer);
> -	drm_client_buffer_flush(scanout->buffer, &r);
>   }
>   
>   static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
> -			      unsigned int len, unsigned int prefix_len)
> +			      unsigned int len, unsigned int prefix_len,
> +			      struct iosys_map map)
>   {
>   	struct drm_framebuffer *fb = scanout->buffer->fb;
> -	struct iosys_map map;
>   	const struct font_desc *font = scanout->font;
>   	size_t font_pitch = DIV_ROUND_UP(font->width, 8);
>   	const u8 *src;
> @@ -136,10 +132,9 @@ static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
>   					  fb->width, (scanout->line + 1) * scanout->scaled_font_h);
>   	u32 i;

same here, the drm_rect r, can be removed.>
> -	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
> -		return;
>   
>   	iosys_map_incr(&map, r.y1 * fb->pitches[0]);
> +
>   	for (i = 0; i < len && i < scanout->columns; i++) {
>   		u32 color = (i < prefix_len) ? scanout->prefix_color : scanout->front_color;
>   		src = font_data_glyph_buf(font->data, font->width, font->height,
> @@ -154,21 +149,40 @@ static void drm_log_draw_line(struct drm_log_scanout *scanout, const char *s,
>   	scanout->line++;
>   	if (scanout->line >= scanout->rows)
>   		scanout->line = 0;
> -	drm_client_buffer_vunmap_local(scanout->buffer);
> -	drm_client_buffer_flush(scanout->buffer, &r);
>   }
>   
>   static void drm_log_draw_new_line(struct drm_log_scanout *scanout,
> -				  const char *s, unsigned int len, unsigned int prefix_len)
> +				  const char *s, unsigned int len,
> +				  unsigned int prefix_len)
>   {
> +	struct iosys_map map;
> +	struct drm_framebuffer *fb = scanout->buffer->fb;
> +	u32 height = scanout->scaled_font_h;
> +	u32 line = scanout->line;
> +	u32 y2;
> +	struct drm_rect dirty;
> +
> +	if (drm_client_buffer_vmap_local(scanout->buffer, &map))
> +		return;
> +
>   	if (scanout->line == 0) {
> -		drm_log_clear_line(scanout, 0);
> -		drm_log_clear_line(scanout, 1);
> -		drm_log_clear_line(scanout, 2);
> -	} else if (scanout->line + 2 < scanout->rows)
> -		drm_log_clear_line(scanout, scanout->line + 2);
> +		drm_log_clear_line(scanout, 0, map);
> +		drm_log_clear_line(scanout, 1, map);
> +		drm_log_clear_line(scanout, 2, map);
> +		y2 = min(3, scanout->rows) * height;
> +	} else if (scanout->line + 2 < scanout->rows) {
> +		drm_log_clear_line(scanout, scanout->line + 2, map);
> +		y2 = (line + 3) * height;
> +	} else {
> +		y2 = (line + 1) * height;
> +	}
> +
> +	drm_log_draw_line(scanout, s, len, prefix_len, map);
> +
> +	drm_client_buffer_vunmap_local(scanout->buffer);
>   
> -	drm_log_draw_line(scanout, s, len, prefix_len);
> +	dirty = DRM_RECT_INIT(0, line * height, fb->width, y2 - line * height);
> +	drm_client_buffer_flush(scanout->buffer, &dirty);
>   }
>   
>   /*